U.S. patent application number 12/162980 was filed with the patent office on 2009-07-23 for submersible plant.
This patent application is currently assigned to Minesto AB. Invention is credited to Magnus Landberg.
Application Number | 20090185904 12/162980 |
Document ID | / |
Family ID | 36754214 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090185904 |
Kind Code |
A1 |
Landberg; Magnus |
July 23, 2009 |
SUBMERSIBLE PLANT
Abstract
The present invention relates to a submersible plant for
producing energy. The submersible plant comprises at least one
turbine (9) and is characterized in that said turbine (9) is
mounted on a stream-driven vehicle (3) and in that said
stream-driven vehicle is secured in a structure by means of at
least one wire (6).
Inventors: |
Landberg; Magnus;
(Linkoping, SE) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
425 MARKET STREET
SAN FRANCISCO
CA
94105-2482
US
|
Assignee: |
Minesto AB
Goteborg
SE
|
Family ID: |
36754214 |
Appl. No.: |
12/162980 |
Filed: |
January 31, 2007 |
PCT Filed: |
January 31, 2007 |
PCT NO: |
PCT/EP07/50924 |
371 Date: |
December 4, 2008 |
Current U.S.
Class: |
416/131 ;
290/54 |
Current CPC
Class: |
F05B 2240/97 20130101;
F05B 2240/917 20130101; F03B 17/00 20130101; Y02E 10/20 20130101;
Y02E 10/30 20130101; F05B 2240/9174 20200801; Y02E 10/70 20130101;
Y02E 10/728 20130101; F03D 5/00 20130101; F03B 17/061 20130101;
F03B 17/06 20130101 |
Class at
Publication: |
416/131 ;
290/54 |
International
Class: |
F03B 17/06 20060101
F03B017/06; F03B 13/10 20060101 F03B013/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 2, 2006 |
EP |
06101208.4 |
Claims
1. A submersible plant (1) for producing energy comprising at least
one turbine (9; 18, 19), characterized in that said turbine (9; 18,
19) is mounted on a stream-driven vehicle (3) and in that said
stream-driven vehicle is secured in a structure (4) by means of at
least one wire (6).
2. A submersible plant (1) according to claim 1, wherein the stream
driven vehicle (3) has at least one wing.
3. A submersible plant (1) according to claim 1, wherein the
vehicle (3) is substantially free swiveling at least in a pitch
direction in relation to each turbine (9; 18, 19).
4. A submersible plant (1) according to claim 3, wherein the
vehicle (3) is substantially free swiveling in a roll direction in
relation to at least one of the turbines (9; 18, 19).
5. A submersible plant (1) according to claim 3, wherein at least
one of the turbines (9; 18, 19) is mounted on the vehicle (3) via a
rod (10), and in that a swivel coupling (8) is mounted at one end
of the rod (10) for pivotally connecting either the turbine (9) or
the vehicle (3) to the rod.
6. A submersible plant (1) according to claim 5, wherein the swivel
coupling (8) comprises a universal bearing.
7. A submersible plant (1) according to claim 3, wherein at least
one of the turbines (18, 19) is directly mounted on the vehicle by
means of a swivel coupling.
8. A submersible plant (1) according to claim 1, wherein the
stream-driven vehicle (3) is provided with steering means (16, 17)
and in that a control unit (15) is arranged to provide control
signals to the steering means (16, 17) for steering the vehicle in
a predetermined trajectory (7).
9. A submersible plant (1) according to claim 8, wherein the
predetermined trajectory (7) is formed in a spherical surface at
least partly crossing the stream-direction.
10. A submersible plant (1) according to claim 8, wherein said
steering means (16, 17) includes at least one control surface.
11. A submersible plant (1) according to claim 1, wherein the
turbine (9; 18, 19) is operatively connected to a generator
arranged to produce electrical energy.
12. A submersible plant (1) according to claim 11, wherein the
generator is operatively connected to an electrical cable (12)
arranged to distribute said electrical energy.
13. A submersible plant (1) according to claim 12, wherein said
electrical cable (12) is at least partly integrated in the wire
(6).
14. A submersible plant (1) according to claim 4, wherein at least
one of the turbines (9; 18, 19) is mounted on the vehicle (3) via a
rod (10), and in that a swivel coupling (8) is mounted at one end
of the rod (10) for pivotally connecting either the turbine (9) or
the vehicle (3) to the rod.
Description
TECHNICAL AREA
[0001] The present invention relates to a submersible plant for
producing energy comprising at least one turbine.
DESCRIPTION OF PRIOR ART
[0002] One of the main global problems to be solved is how to
supply energy to the population of the world. The use of fossil
fuels has to be decreased and substituted with renewable sources of
energy.
[0003] A significant percentage of the efforts to use renewable
sources of energy have been concentrated on wind powered systems.
The wind powered generating systems have a problem in that wind
energy is inherently intermittent.
[0004] There exist today submersible plants for producing
electricity from ocean currents. Those plants are fastened in the
sea bottom by means of wires and comprise turbines arranged to be
driven by tidal water.
[0005] However, the power generated from the submersible plants
needs to be increased without substantially increasing the costs in
order to be commercially attractive.
DESCRIPTION OF THE INVENTION
[0006] One object to the invention is to increase the power output
from submersible plants.
[0007] This has been achieved by means of a submersible plant for
producing energy comprising at least one turbine and characterized
in that said turbine is mounted on a stream-driven vehicle and in
that said stream-driven vehicle is secured in a structure by means
of at least one wire. The structure can be stationary, such as a
mooring at the bottom of a sea, river, lake etc or a wind power
plant or stationary submersible plant located in a sea or lake. The
structure can also be movable, such as a ship.
[0008] The vehicle of the plant according to the present invention
moves with a velocity which is many times (characteristically
between 10-20 times) higher than the streaming velocity of the
water. Thereby, the efficiency of the on board turbine arrangement
is much higher than the efficiency of a stationary rotor
arrangement.
[0009] The plant is preferably mounted in environments with
well-defined, predictable streams with regard to direction and
velocity such as in rivers, in tide affected areas and in ocean
streams.
[0010] The plant in accordance of the invention enables environment
friendly, rational and cost effective generation of energy, for
example electrical energy, from relatively weak ocean currents and
tide streams on cites close to the coast. The plant in accordance
with the present invention can also be used offshore at relatively
large depths, where few competing techniques are available.
[0011] In accordance with one preferred embodiment of the present
invention the stream driven vehicle is a wing, ie a lifting
body.
[0012] The vehicle is in accordance with another preferred
embodiment substantially free swiveling at least in a pitch
direction. The vehicle adapts to an optimum working point in the
pitch direction. The vehicle is preferably also free swiveling in a
roll direction in relation to the turbine. Thereby the turbine will
face the relative stream direction, ie the water stream will be
forced upon the turbine from a direction perpendicular to a plane
defined by the turbine blades.
[0013] In one preferred embodiment wherein the vehicle is free
swiveling in accordance with the above, at least one of the
turbines is mounted on the vehicle via a rod and a swivel coupling
is mounted at one end of the rod for pivotally connecting either
the turbine or the vehicle to the rod. The swivel coupling
comprises for example a universal bearing.
[0014] In another preferred embodiment wherein the vehicle is free
swiveling in accordance with the above, at least one of the
turbines is directly mounted on the vehicle by means of a swivel
coupling.
[0015] In yet another preferred embodiment of the invention the
stream-driven vehicle is provided with steering means and a control
unit is arranged to provide control signals to the steering means
for steering the vehicle in a predetermined trajectory. The
steering means can then include one or more control surfaces.
[0016] Further, the wire will preferably be stretched and
accordingly the predetermined trajectory is formed in a spherical
surface. In order to provide the stream-driving, the predetermined
trajectory will at least partly cross the stream-direction.
[0017] In accordance with one embodiment of the invention, the
turbine is operatively connected to a generator arranged to produce
electrical energy. The generator can be operatively connected to an
electrical cable arranged to distribute said electrical energy. The
electrical cable is for example at least partly integrated in the
wire. However, if an electrical cable connecting to the vehicle is
not desirable, the produced electrical energy can for example be
used for electrolyzing the water and production of hydrogen gas
directly at the vehicle.
BRIEF DESCRIPTION OF FIGURES
[0018] FIG. 1a shows an example of a submersible plant arrangement
in accordance with a first example of the invention in a xy-plane,
wherein x denotes a horizontal direction perpendicular to the
stream direction and y denotes the vertical direction.
[0019] FIG. 1b shows the submersible plant arrangement of FIG. 1a
in a yz-plane, wherein z denotes a horizontal stream direction.
[0020] FIG. 1c shows the submersible plant arrangement of FIG. 1a
in a xz-plane.
[0021] FIG. 2 shows a first example of a stream driven vehicle of
the submersible plant of FIG. 1.
[0022] FIG. 3 shows in cross-section an example of a wire of the
submersible plant of FIG. 1.
[0023] FIG. 4 shows an example of a mounting of a turbine to the
vehicle of the submersible plant of FIG. 1.
[0024] FIG. 5 shows an example of a control unit of the submersible
plant of FIG. 1.
[0025] FIG. 6a shows an example of a submersible plant arrangement
in accordance with a second example of the invention in a xy-plane,
wherein x denotes a horizontal direction perpendicular to the
stream direction and y denotes the vertical direction.
[0026] FIG. 6b shows the submersible plant arrangement of FIG. 6a
in a yz-plane, wherein z denotes a horizontal stream direction.
[0027] FIG. 6c shows the submersible plant arrangement of FIG. 6a
in a xz-plane.
[0028] FIG. 7 shows a second example of a stream driven vehicle of
the submersible plant of FIG. 1.
PREFERRED EMBODIMENTS
[0029] In FIGS. 1a, 1b and 1c, a submersible plant 1 is arranged
under the water surface 2 of for example the sea. The plant 1
comprises a stream-driven vehicle 3 secured in a mooring 4 at the
bottom 5 of the sea by means of a wire 6. The length of the wire 6
is for example 50-200 meters. In FIG. 1a, z defines the horizontal
stream direction, x a horizontal direction perpendicular to the
stream direction and y defines the vertical direction. The vehicle
can move freely within a range of the wire. However, in FIGS. 1a,
1b and 1c, the vehicle follows a never-ending trajectory 7 formed
as the digit eight in a spherical surface with a bending radius
equal to the length of the wire. The trajectory is preferably
chosen such that the vehicle is always is beneath the sea surface.
For example, the trajectory can be chosen such that the wire always
ends 10-20 meters beneath the sea surface. Thereby the vehicle is
not subjected to the turbulences usually present close to the
surface and the risk of turbine cavitation can be minimized. The
advantage of having a trajectory formed as the digit eight is that
then the wire will not be twisted and accordingly, there is no need
for connecting the wire 6 to the mooring 4 by means of a swiveling
device
[0030] In FIG. 2 the stream-driven vehicle 3 is a wing, ie a
lifting body. The wing has for example a wing span s of about 15
meters and a width (cord) c which is for example 2-3 meters. The
thickness of the wing may be 10-20% of the width. The wing is
preferably formed by a spar supporting a surface structure. The
spar is in one example made of a carbon fibre composite material.
The surface structure is for example made of a glass fibre
composite material.
[0031] A turbine arrangement 9, in the illustrated embodiment
comprising one turbine, is mounted to the vehicle structure by
means of a rod 10. The turbine 9 and rod 10 can be made of a metal
or compound of metals, for example stainless steal. In one example,
the turbine 9 has adjustable blades and in another example, the
blades of the turbine 9 are fixedly mounted. The diameter of the
turbine is for example 1 to 1.5 meters. The wire 6 is secured in
the turbine 9. The turbine 9 is operatively connected to a
generator (not shown) arranged to produce electrical energy
distributed via an electrical cable integrated within or secured to
the wire. In one example, the generator is speed controlled and in
another example, the generator is not speed controlled. The
electricity is distributed further from the mooring 4 via a
distribution network.
[0032] The density of the vehicle 3 with its turbine 9, rod 10 and
wire 6 is preferably somewhat lower than the density of water.
[0033] In FIG. 3 the wire 6 comprises two supporting twisted cables
11a, 11b for example made of a carbon fiber material and the
electrical cable 12. The wire further comprises an additional
electrical low voltage or optical cable 13 for data communication
with the vehicle 3. The supporting cables 11a, 11b, electrical
cable 12 and low voltage or optical cable 13 are enclosed in a
cover 14, for example made of a rubber material or plastic.
[0034] The vehicle 3 is preferably powered only by the stream.
However, in certain situations, for example when an error condition
has appeared, the electrical generator can be used as an electrical
engine powered by one or several batteries (not shown) mounted at
the vehicle. Then, the generator/engine can drive the vehicle to
the sea surface for transportation to a service site. This of
course presumes that the vehicle first has been released from the
wire. The generator can be used as an engine also for other
purposes, for example for driving the vehicle to a parking location
at the sea bottom.
[0035] In FIG. 4, the rod 10 is mounted to the vehicle 3 by means
of a bearing arrangement 8 so that the vehicle is free swiveling at
least in pitch direction but preferably also in roll direction.
Preferably, the relationship between the turbine and the vehicle is
fixed in yaw direction. The fact that the vehicle is free swiveling
in relation to the turbine secures that the turbine arrangement
always substantially faces the relative stream direction, ie the
stream direction is perpendicular to a plane defined by the turbine
blades. In FIG. 4, the bearing arrangement is a universal bearing.
The universal bearing provides for the free swiveling feature in
pitch and roll direction. In the example illustrated in FIG. 4, the
turbine is fixedly mounted to the rod, or integrated therewith
while the other end of the rod facing the vehicle is mounted to the
vehicle by means of the bearing arrangement 8. However, in an
alternative example (not shown) the bearing arrangement 8 is
mounted at the end of the rod facing the turbine. In yet another
example (not shown), the turbine is fixedly mounted to the rod or
integrated therewith and the other end of the rod facing the
vehicle is fixedly mounted to the vehicle or integrated
therewith.
[0036] In FIG. 5, a control system 15 mounted on the vehicle is
arranged to guide the vehicle in the predetermined trajectory 7
without exceeding the structural load limitations on the vehicle
and turbine and electrical load limitations on the turbine. Other
functional requirements of the control system 15 are to stabilize
the vehicle 3 and optimize or control the power output of the
device in the never-ending trajectory 7.
[0037] The control system 15 has in the shown example four input
signals for guidance and tracking. The first input signal, namely
current tilt angle .alpha. (see FIG. 1b), and the second input
signal, namely current rotational angle .beta. (see FIG. 1c), are
provided from angle detecting devices (not shown) mounted at the
mooring 4 of the wire 6 and fed for example via the previously
described electrical cable 13 in the wire 6 to the control system
15. The first, tilt angle signal .alpha. defines the angle between
the wire 6 and the horizontal plane. The second, rotational angle
signal .beta. defines the angle between the wire 6 and the
horizontal stream direction. Two angle measuring arrangements are
further mounted in the vehicle bearing arrangement 8. These two
angle measuring devices are arranged to provide a third input
signal to the control system indicating a roll angle between the
vehicle 3 and rod 10 and to provide a fourth input signal
indicating a pitch angle between the vehicle 3 and the rod 10.
Further sensor data can for example be provided from an inertial
measurement unit at the vehicle for refining the computations of
the control system 15. The further sensor data can also relate to
the water depth.
[0038] The tilt angle data .alpha., rotational angle data .beta.,
roll angle data and pitch angle data are processed by the control
system and a command angle is outputted for a first control surface
16 (FIG. 2) of the vehicle 3 and a command angle for the second
control surface 17 of the vehicle 3. In processing, values are
calculated for pitch and yaw movements required by the vehicle in
order to follow the predetermined trajectory. The control system
then provides in a second step a command angle for each servo
actuator (not shown) mounted on its corresponding control surface
16, 17. The hydrodynamic forces on the control surfaces then cause
the vehicle and turbine to yaw and roll in order to follow the
predetermined trajectory. The algorithms for calculating command
angles for the first and second surfaces 16, 17 do not form part of
the present invention. It would constitute normal operations to a
person skilled in the art to provide an algorithm for guiding a
vehicle in accordance with the above in a predetermined trajectory
under given physical conditions. However, it can be said that the
force and tension in the wire is very high when the vehicle
operates in its trajectory. Accordingly, in determining the command
angles for the control surfaces 16, 17, the wire 6 can be
approximated as a linear rod.
[0039] In FIGS. 6a, 6b, 6c, an example of an alternative never
ending trajectory 7 of the vehicle 3 is shown in the same
coordinate system as in FIG. 1. The trajectory illustrated in FIGS.
6a, 6b and 6c is formed as an oval. The illustrated never ending
trajectory requires a swiveling device at the mooring 4 in order to
avoid twisting the wire.
[0040] In FIG. 7 the vehicle is provided with two additional
turbines 18, 19, one at each end of the vehicle. The turbines are
mounted to the vehicle by means of a bearing allowing the turbines
to be free swiveling in a pitch direction. An electrical generator
arranged to produce electrical energy is connected to each turbine.
A cable connects each additional turbine generator to the
electrical cable 12 of the wire 6 for further distribution.
[0041] The vehicle is in the illustrated examples a wing. However,
the invention is not limited to a vehicle in the form of a wing.
For example, the vehicle can be formed by two or more wings
arranged on top of each other and separated by means of spacer
elements.
* * * * *